Janner et al U.S. Pat. No. 3,444,400, Hobson U.S. Pat. No. 3,548,222, and Gross et al U.S. Pat. No. 3,578,991 disclose thermionic converter fuel elements. The thermionic converters are heated by inserting the fuel elements directly into the cores of nuclear reactors.
The thermionic converter disclosed in Rasor et al U.S. Pat. No. 3,983,423 has a heat source for heating an emitter. This heat source may be a nuclear reactor fuel element, hot liquid metal flowing in a tube, or other means.
Leventhal U.S. Pat. No. 3,451,641 teaches the use of a heat pipe to transfer heat from a nuclear reactor to a thermal electric converter.
Leffert U.S. Pat. No. 3,621,906 is directed to a control system for heat pipes which assures electrical conduction between the input and output heat pipes. A complex structure is relied on to vary the rate of heat transport between the heat source, such as a heat pipe, and a heat sink, which may be another heat pipe.
Grover et al patent No. 3,302,042 is directed to a nuclear heat source having a thermionic converter load. The heat pipes in the reactor are joined by solid materials.
Byrd U.S. Pat. No. 3,537,515 describes a power system having a number of thermionic diodes connected in parallel. The diodes use heat pipes as cathodes.